JPH03682B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an auto-tuning method for automatically adjusting recording level and bias amount in a magnetic recording/reproducing apparatus such as a tape recorder.

Generally, in a magnetic recording/reproducing device employing a high frequency bias recording method such as a tape recorder, adjustment is required to set the bias amount to an appropriate value depending on the type of magnetic tape used. A bias amount adjustment method is well known in which this adjustment is automated using a digital control unit using a microcomputer, and can automatically handle different types of magnetic tapes. For example, a bias oscillation circuit that oscillates a sine wave with a frequency of about 1KHz and whose output, that is, the amount of bias, can be varied in steps, and a mid-range frequency signal (1KHz) and a high-range frequency signal (10KHz) that serve as reference signals to be recorded. A sine wave oscillation circuit that oscillates, a recording and reproducing circuit that superimposes the bias signal on the medium and high frequency signal outputs of the sine wave oscillator circuit to record and reproduce the signals, and a reproduction output level from the recording and reproducing circuit. It has a built-in automatic bias adjustment device equipped with an A/D converter that converts the signal into a digital signal, and a control section that digitally controls each of the circuits according to the output of the A/D converter, and a bias oscillation circuit. The appropriate value of the bias amount has been automatically detected by repeating the recording/reproduction test while sequentially varying the bias amount. There has also been a recording level adjustment method that automatically sets the recording level amount to an appropriate value depending on the type of magnetic tape used.

Therefore, conventionally, an auto-tuning method has been devised in which bias amount adjustment and recording level adjustment are automatically performed as one process. In this method, coarse recording level adjustment, bias adjustment, and recording level adjustment are performed in this order, but you cannot move on to the next adjustment until one adjustment is completed, so all adjustments must be completed completely. The drawback was that it took quite a while.

The present invention has been made to eliminate the drawbacks of the conventional methods described above, and is an automatic method that can simultaneously perform the coarse recording level adjustment, bias adjustment, and recording level adjustment described above, and complete the adjustment in a short time. The aim is to provide a tuning method.

An embodiment of the present invention will be described below with reference to the drawings. In Figure 1, 1 is the mid-range frequency (1KHz)
A sine wave oscillation circuit that oscillates a signal, 2 is a sine wave oscillation circuit that oscillates a high frequency (10KHz) signal, SW ₁
3 is an input terminal for inputting a signal to be recorded; 4 is a recording level variable device for varying the recording level; 5 is a recording amplifier that amplifies the signal input from the input terminal 3; 6 is a bias oscillation circuit that can vary the amount of bias; the output of this is superimposed on the latter stage of the recording amplifier 5, and is recorded on the magnetic tape 8 by the recording head 7. be done. Reference numeral 9 denotes a reproduction head for reproducing the signal recorded on the magnetic tape 8 by the recording head 7, 10 a reproduction amplifier for amplifying the signal reproduced by the reproduction head 9, and 11 outputting the output signal of the reproduction amplifier. an output terminal; 12 is an A/D converter that converts the output signal of the reproduction amplifier into a digital signal; 13 is a data storage circuit that stores the digital signal on which the mid-range frequency signal has been superimposed; 14
1 is a data storage circuit that stores a digital signal on which a high frequency signal is superimposed, and SW ₂ is a switch that inputs the output of the A/D converter 12 to either of the data storage circuits 13 and 14. 15 is-
a reference signal generation circuit that generates a signal at a level of 20VU as a reference signal; 16 is the data storage circuit 1;
a comparison circuit 1 that compares the output of the reference signal generation circuit 15 with the output of the reference signal generation circuit 15 and outputs a difference signal and a positive/negative signal;
7 is a calculation circuit that calculates the signal from the comparison circuit 16 and determines a level correction signal; if the difference signal from the comparison circuit 16 is within a certain range, it outputs a level data OK signal to the AND circuit 22; do.
18 is a level data addition circuit that adds the level correction signal obtained by the arithmetic circuit 17 and the level signal corresponding to the center of the variable range of the recording level amount, stores the result, and outputs the output to the recording level variable device 4; , 19 are the data storage circuits 13, 14
20 is a calculation circuit that calculates the signal from the comparison circuit 19 and determines a bias correction signal; If the value is within a certain range, a bias data OK signal is output to the AND circuit 22. 21 is a bias data addition circuit that adds the bias correction signal obtained by the arithmetic circuit 20 and the bias signal corresponding to the center of the variable range of the bias amount, stores the result, and outputs the output to the bias oscillation circuit 6. . Reference numeral 23 denotes a control circuit, which is activated by turning on the switch SW _3. First, it sends a signal to the mechanical control circuit 24 to operate the mechanism necessary for recording, and when recording becomes possible, the switch is activated. Switch SW ₁ is controlled to alternately superimpose a medium frequency signal and a high frequency signal on the input signal, and switch SW ₂ is controlled to transfer the output of the A/D converter 12 to the data storage circuit 1.
Enter either 3 or 14. Further, a level signal and a bias signal corresponding to the center of the variable range are supplied to the level data addition circuit 18 and bias data addition circuit 21, respectively. Further, the level data OK signal and the bias data OK signal from the arithmetic circuit 17 and the arithmetic circuit 20 are sent to an AND circuit 22.
The signal is supplied to the control circuit 23 through the autotuning.

In the above configuration, when the switch SW ₃ is pressed, the control circuit 23 is activated and sends a signal to the mechanical control circuit 24 to activate the mechanism and become ready for recording. Then, the switch SW ₁ is controlled, and the medium frequency signal from the sine wave oscillation circuit 1 and the high frequency signal from the sine wave oscillation circuit 2 are controlled within a variable range of the bias oscillation circuit 6 and the recording level variable device. The data is alternately recorded on the magnetic tape 8 via the recording amplifier 5 and the recording head 7 with a bias amount and a recording level amount of the center value. Next, in the reproduction head 9, the middle frequency signal and the high frequency signal alternately recorded on the magnetic tape 8 are corrected, and these signals are sent to the output terminal 1 via the reproduction amplifier 10.
1 and simultaneously supplied to the A/D converter 12, where it is converted into a digital signal. The digital signal obtained by the A/D converter 12 is separated by the switch SW ₂ , and the medium frequency signal is supplied to the data storage circuit 13 and the high frequency signal is supplied to the data storage circuit 14, respectively. The timing of the control of the switch _SW2 is obtained by delaying the timing of the control of the switch _SW1 by the time it takes for the tape to run between the recording head 7 and the playback head 9. The mid-range frequency signal supplied to the data storage circuit 13 is stored here and further supplied to the comparison circuits 16 and 19. The comparison circuit 16 compares the intermediate frequency signal from the data storage circuit 13 and the reference signal (-20VU) from the reference signal generation circuit 15, and outputs the difference in level as an absolute value. If the mid-range frequency signal is larger than the reference signal, a negative signal is sent to the arithmetic circuit 17; if the reference signal is larger than the mid-range frequency signal, a positive signal is sent to the arithmetic circuit 17.
supply to. Next, the arithmetic circuit 17 calculates the difference signal and the positive/negative signal from the comparator circuit 16 to determine a level correction signal, and supplies this to the level data addition circuit 18. If the value is , a level data OK signal is supplied to the AND circuit 22. Furthermore, the level data addition circuit 18 adds the level correction signal described above and the level signal from the control circuit 23, and outputs this to the recording level variable device 4 to adjust the recording level.

Further, the high frequency signal supplied to the data storage circuit 14 is stored here and further applied to the comparison circuit 19. The comparator circuit 19 compares the middle frequency signal and the high frequency signal from the data storage circuits 13 and 14 and outputs the difference in level as an absolute value, and also indicates that the middle frequency signal is the high frequency signal. If the high frequency signal is greater than the middle frequency signal, a positive signal is supplied to the arithmetic circuit 20, and conversely, if the high frequency signal is greater than the middle frequency signal, a negative signal is supplied to the arithmetic circuit 20. The calculation circuit 20 calculates the difference signal and the positive/negative signal from the comparison circuit 19 to determine a bias correction signal,
This is supplied to the bias data addition circuit 21, and if the difference signal has a value within a certain range, a bias data OK signal is supplied to the AND circuit 22. Furthermore, the bias data addition circuit 21 adds the bias correction signal described above and the bias signal from the control circuit 23, and outputs this to the bias oscillation circuit 6 to adjust the amount of bias.

Record and play again with the recording level and bias amount adjusted as above, and the level data is OK.
The signal and bias data OK signal are output at the same time.
This is repeated until the AND circuit 22 operates to stop the operation of the control circuit.

Next, the process of adjustment as described above will be specifically explained using FIG. 2. Suppose that when a signal like the one shown in (A) is recorded, a signal like the one shown in (A)' is reproduced.
In (A)′, the mid-frequency (1KHz) signal is α, dB lower than the reference signal level (−20VU),
Mid frequency (1KHz) signal is high frequency (10KHz)
Since β, dB is higher than that of the signal shown in (A), the next recording signal is as shown in (B).
In other words, the recording level is increased and the bias is adjusted to become a deeper signal. Furthermore (B)
Suppose that when a signal like that shown in (B)' is recorded, a signal like (B)' is reproduced. In (B)′, the mid-frequency signal is α ₂ dB higher than the reference signal level;
Since the mid-range frequency signal is β ₂ dB higher than the high-range frequency signal, the next recorded signal will be α ₂ dB higher than the mid-range frequency signal of the signal shown in (B), as shown in (C). The signal is subtracted and adjusted so that it becomes a signal obtained by adding β ₂ dB to the high frequency signal. Furthermore, when a signal like that shown in (C) is recorded, a signal like (C)' is reproduced. In the signal shown in (C)', the mid-range frequency signal is equal to the reference signal, and the mid-range frequency signal is almost equal to the high-range frequency signal (the difference β ₃ dB is sufficiently small).
Therefore, the bias data OK signal and level data OK signal are output here, and the adjustment is completed.

As described above, the present invention includes a bias oscillation circuit 6 that can vary the amount of bias in steps, a recording level variable device 4 that can vary the amount of recording level in steps, and a sine oscillation circuit that oscillates a mid-range frequency signal and a high-range frequency signal. wave oscillation circuits 1 and 2, a recording/reproducing amplifier 5 for recording and reproducing the superimposed output of each frequency range of the sine wave oscillation circuits 1 and 2 and the output of the bias oscillation circuit, a recording head 7, and a reproducing head 9. and a recording/reproducing circuit composed of a reproduction amplifier 10 and the like, an A/D converter 12 that converts the reproduction output level from the recording/reproducing circuit into a digital signal, and a An auto-tuning method for automatically adjusting the bias amount and recording level amount of a magnetic recording/reproducing device using an auto-tuning device equipped with a bias oscillation circuit 6 and a control unit that digitally controls a recording level variable device 4. First, the bias oscillation circuit 6 and the recording level variable device 4 are
A mid-range frequency signal and a high-range frequency signal are respectively recorded and played back with the bias amount and recording level amount at approximately the center step of the bias amount variable step number and the recording level amount variable step number, respectively, and the playback output levels are compared. If the output levels of both frequency ranges are approximately equal, the bias amount at the time of the test is set as the appropriate value, and if the output level of the high frequency range is higher than the output level of the middle frequency range, the bias amount of both of the above-mentioned initial bias values is set as the appropriate value. The bias amount is shallower by the difference in level, and if the output level in the middle frequency range is higher than the output level in the high frequency range, the bias amount is deeper than the initial bias amount by the difference between the two levels. Perform the same test again, and by repeating this, when the reproduction output levels of the mid-range frequency signal and the high-frequency signal are almost equal, the bias amount is set to an appropriate value, and at the same time, the reproduction output of the mid-range frequency signal is adjusted to the appropriate value. Compare the level with the output level of the reference signal, and if both output levels are approximately equal, the recording level amount at the time of the test is considered to be the appropriate value, and if the output level of the mid-frequency range is higher than the output level of the reference signal The recording level amount is obtained by subtracting the difference between the two levels from the original recording level amount, and if the output level of the reference signal is higher than the output level of the mid-range frequency range, the difference between the two levels is subtracted from the initial recording level amount. Perform the same test again with the recording level amount added by the difference, and by repeating this, the recording level amount when the playback output level of the mid-range frequency signal and the output level of the reference signal become almost equal is determined as the appropriate value. Therefore, recording level adjustment and bias adjustment can be performed at the same time, and the adjustment can be completed in a short time.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is an explanatory diagram illustrating the adjustment process in the present invention. 1, 2... Sine wave oscillation circuit, 4... Recording level variable device, 5... Recording amplifier, 6... Bias oscillation circuit, 7... Recording head, 9... Playback head, 1
0...Reproduction amplifier, 12...A/D converter.

Claims (1)

[Claims] 1. A bias oscillation circuit that can vary the amount of bias in steps, a recording level variable device that can vary the amount of recording level in steps, a sine wave oscillation circuit that oscillates mid-range frequency signals and high-frequency signals, and this sine wave a recording/reproducing circuit for recording and reproducing the outputs of each frequency range of the oscillation circuit and the output of the bias oscillation circuit in a superimposed manner; and an A/D converter for converting the reproduction output level from the recording/reproducing circuit into a digital signal. The bias amount and recording level of the magnetic recording/reproducing device are adjusted using an auto-tuning device that includes a control unit that digitally controls the bias oscillation circuit and the recording level variable device according to the output of the A/D converter. In an auto-tuning method for automatically adjusting the amount, first, the bias amount and recording level amount are determined at approximately the center step of the number of bias amount variable steps and the number of recording level variable steps of the bias oscillation circuit and recording level variable device, respectively. Record and playback the mid-range frequency signal and the high-range frequency signal respectively, and compare the playback output levels. If the output levels of both frequency ranges are approximately equal, set the bias amount at the time of the test to an appropriate value, and If the output level of the mid-range frequency range is higher than the output level of the mid-range frequency range, the bias amount is shallower than the initial bias amount by the difference between the two levels, and the output level of the mid-range frequency range becomes the output level of the high-range frequency range. If it is larger than the level, perform the same test again with a bias amount that is deeper than the initial bias amount by the difference between the two levels,
By repeating this, when the reproduction output level of the mid-range frequency signal and the high-frequency signal are almost equal, the bias amount is set to an appropriate value, and at the same time, the reproduction output level of the mid-range frequency signal and the output level of the reference signal are If both output levels are approximately equal, the recording level amount at the time of the test is taken as the appropriate value, and if the output level in the mid-range frequency range is higher than the output level of the reference signal, the above recording level amount is changed from the original recording level amount. The recording level amount is subtracted by the difference between the two levels.
If the output level of the reference signal is higher than the output level of the mid-range frequency range, perform the same test again with a recording level amount added by the difference between the two levels from the initial recording level amount, and repeat this. An auto-tuning method characterized in that the recording level amount when the playback output level of the mid-range frequency signal and the output level of the reference signal become approximately equal is set to an appropriate value.